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Circular  No   11 


United  States  Department  <>!'  ViyrftMiltnn1 

BUREAU  OP    1  N  rOMOl  OOY) 

I     1 1    HOWARD    . 


NUN    ON     I  III     llll  I  l.'l.'l  M  I     o|      llll     Nol.'lll     \l||  IMI   \>    IKU.U  Tl<  k 

ON   sin  1  p, 


By  W.  I>.  Hi  si. 
/,    Chargt  of  Cotton  Boll  Weei'il  Inrentigatiot 

There  are  no  published  records  of  the  finding  of  specimens  of  the 
North  American  fever  tick  [Hoophilus  annulatus  Say)  mm  iheep.  In 
enerally  been  supposed  that  this  species  dot  -  nol  occur  on 
Bheep,  although  Mr.  B.  II.  Ransom  has  surmised  that  Buch  might  In- 
tin-  case.1  In  connection  with  the  tick  work  <>f  the  Bureau  of  Entomol- 
m  agent,  Mr.  J.  I>.  Mitchell,  has  recently  obtained  data  which 
indicate  a  rather  general  occurrence  of  the  fever  tick  on  sheep.  On 
account  of  the  considerable  practical  importance  of  this  matter  it  is 
thought  advisable  to  publish  this  preliminary  note. 

The  practical  importance  of  the  discovery  made  by  Mr.  Mitchell  lie- 
in  the  fact  that  the  dissemination  of  ticks  by  Bheep  may  play  a  very 
important  part  in  the  work  ol  eradication  that  is  now  under  way.  In 
the  general  work  of  the  eradication  frequenl  use  must  be  made  of  the 
"starvation"  plan  under  which  the  cattle  arc  removed  from  pastures 
for  a  considerable  time.  In  many  parts  of  the  tick-infested  area  most 
of  the  cattle  raisers  have  as  many  cattle  as  they  can  possibly  carry  on 
their  holdings.  To  he  forced  to  dispi  use  with  the  use  of  a  part  of  the 
re  ar.a  in  man;  -      ould  force  the  Bale  of  :l  portion  of  the  cat- 

tle, perhaps  it  an  unfavorable  time  for  marketing.     If.  however,  it  were 
ble   to   allow  Other  kind   of   live    stock  to   ^raze   on   pastures 

from  which  ticks  are  being  eradicated  according  to  the  starvation  plan, 
tile  inconvenience  and  possible  loss  to  the  ranchmen  would  be  consider- 
ably lessened.  Sinc<  th  American  fever  tick  has  previously  not 
been  known  to  in!  p,  it  has  been  thought  that  the  pasture.-  might 
be  used  for  grazing  these  animals.  The  discoveries  made  by  Mr. 
Mitchell,  however,  indicate  that  the  dissemination  of  fever  ticks  by 
sheep  is  of  suoh  practical  importance  that,  at  hast  in  the  parts  of  1 
where  the  matter  has  been  inv  ire  would  remain  int 
indefinitely  even  if  the  sheep  alone  were  allowed  to  roam  over  it.  It  is 
not  .1        -  in  one  part  of  the  pasture 


lCir.  in  of  Animal  Industry,  (7.  8.  I  ber,  1906. 


to  another,  but  a  cast'  of  the  breeding  of  the  fever  ticks  on  sheep,  since 
in  several  cases  fully  engorged  females  have  been  found  on  these  ani- 
mals, and  they  are  now  freely  depositing  eggs. 

The  following  are  some  of  the  particulars  regarding  data  obtained  up 
to  this  time.  The  matter  will  be  followed  up  by  the  Bureau  of  Ento- 
mology, and  a  further  report  will  be  made  at  the  end  of  the  season. 

In  April,  1907,  Mr.  A.  P.  Ward,  of  Jackson  County,  Tex.,  sent  to 
Mr.  J.  I).  Mitchell  a  number  of  specimens  of  Boophilns  annulatus  that 
he  had  taken  from  a  sheep.  In  this  lot  there  was  one  engorged  female 
that  deposited  eggs  which  have  hatched.  Mr.  Ward's  attention  was 
attracted  to  the  matter  by  seeing  this  tick  hanging  in  the  hair  of  one 
fore  leg.  It  was  in  the  act  of  dropping  to  the  ground  for  oviposition. 
At  least  a  dozen  other  specimens  were  then  collected  on  this  animal. 
There  were  five  or  six  nearly  engorged  adult  females,  together  with  sev- 
eral nymphs  and  larva:.  The  sheep  upon  which  these  ticks  were  found 
had  not  been  sheared  this  season,  although  the  wool  was  rather  scant 
on  the  belly.  Nevertheless,  the  ticks  had  made  their  way  well  up  into 
the  thick  wool  on  the  sides  of  the  animal.  Mr.  Ward  notes  that  the 
sheep  was  "  as  oily  as  she  could  be."  The  animal  was  one  which  had 
been  left  in  an  isolated  field  for  a  month  before  the  ticks  were  discov- 
ered. In  moving  the  herd  this  one  had  accidentally  been  left  behind. 
She  was  exceedingly  active,  and  there  were  no  indications  whatever  of 
any  disease.  The  only  fact  which  would  tend  to  indicate  the  possibility 
of  disease  in  this  sheep  transmitted  by  the  ticks  is  that  she  remained 
in  the  same  place  after  the  herd  was  removed.  It  is  barely  possible 
that  she  was  left  behind  on  account  of  weakness  brought  about  by  the 
disease  at  the  time  the  herd  was  removed.  However,  subsequent  evi- 
dence from  other  flocks  fails  to  justify  the  assumption  that  there  may 
have  been  any  disease  in  this  case. 

Earl}'  in  May,  1907,  Mr.  J.  D.  Mitchell  examined  many  sheep  in  the 
flock  belonging  to  Mr.  Ward.  One  adult  female  tick  was  found, 
together  with  six  individuals  just  passing  from  the  nymphal  to  the 
adult  stage.  These  were  on  several  different  animals,  but  all  located 
in  the  ears. 

At  about  the  same  time  three  sheep  in  a  flock  in  Calhoun  County 
were  examined  by  Mr.  Mitchell.  Two  adult  female  ticks  about  ready 
to  drop  to  the  ground  and  one  molting  nymph  were  found  on  these 
three  animals. 

Since  that  time  Mr.  Mitchell  has  examined  ten  sheep  in  a  large  flock 
belonging  to  Col.  J.  C.  Warden,  whose  ranch  is  in  Victoria  County,  Tex. 
On  two  of  these  sheep  specimens  of  Boophilus  annulatus  almost  fully 
engorged  were  found.  They  were  both  located  on  the  head,  near  the 
base  of  the  ear.  Colonel  Warden  states  that  late  in  the  summer  and 
fall  the  fever  ticks  cause  considerable  annoyance  on  his  sheep.  It  is 
necessary  to  treat  them  continuous!}'  to  prevent  damage  from  screw- 


(forms,  which  are  attracted  by  the  wound  lefl  when  the  tick  detachee 
itself  or  by  the  blood  released  when  one  happens  to  be  crushed  on  the 
bosl . 

It  will  be  noted  thai  fully  engorged  specimens  of  the  fever  tick  have 
ii>u  been  found  on  Bheep  by  Mr.  Mitchell  in  three  different  Mocks  in  as 
many  counties  in  southern  Texas.  It  is  expected  that  future  observa- 
tions will  show  a  rather  general  occurrence  on  sheep 

There  are  several  points  of  importance  to  be  determined,  as,  for 
instance,  whether  the  offspring  of  the  ticks  which  have  developed  on 
Bheep  transmit  splenetic  fever  when  placed  on  nonimmune  cattle,  and 
whether  the  sheep  become  diseased  through  the  agency  of  the  ticks.  It 
is  expected  that  the  Bureau  of  Animal  Industry  will  undertake  investi- 
gations in  the  near  future  bearing  on  these  points.     The  purpose  of  this 

circular  is  merely  to  call  attention  t iii.  i-  of  inn liate  practical 

importance. 

li  may  possibly  be  important  to  note  that  there  are  Borne  peculiar 

features    of    the    cattle-tick    problem     in     southern    Texas    this    season. 

Various  conditions  have  caused  unusually  large  numbers  of  ticks  to  be 
present  in  the  Bpring.  According  to  the  testimony  of  cattlemen  the 
ticks  have  never  been  more  abundant  in  the  Bpring  than  they  are  this 
n.  It  is  barely  possible  thai  this  exc<  Bsive  abundance  may  have 
had  something  to  do  with  the  occurrence  of  tick-  on  Bheep,  and  thai 
under  ditTerent  conditions  the  Bheep  would  not  have  become  infested. 
Nevertheless,  it  must  be  remembered  that  in  that  portion  of  T<  \ 

well  as  elsewhere  the  cattle  ticks  are  frequently  as  numerous  in  the  fall 
of  the  year  as  they  have  been  this  Bpring.  In  view  of  the-e  facts  it  -cms 
evident  that  it  will  he  absolutely  necessary  in  plans  for  eradication  to 
exclude  Bheep  from  areas  in  which  an  attempt  is  being  made  to  eradi- 
cate the  tici 

Approved : 

James  Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C,  Jum  v>,  1907. 

O 


UNIVERSITY  OF  FLORIDA 


3  1262  09216  4622 


